Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of ground fault indication
Patent
1990-08-31
1991-12-03
Harvey, Jack B.
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of ground fault indication
324133, 324126, 324556, 340664, G01R 3102, G08B 2100
Patent
active
050703013
ABSTRACT:
A fault indicator for indicating the occurrence of a fault current in a monitored electrical conductor of an AC power distribution system utilizes a liquid crystal display having independent "F" and "N" display elements. A rectifier circuit capacatively coupled to the conductor charges a first capacitor in the presence of voltage on the conductor. A second capacitor is connected to the first capacitor by a first reed switch in magnetic communication with the conductor. Upon occurrence of a fault current the reed switch closes and a portion of the charge on the first capacitor is transferred to the second capacitor, which is connected to the "F" display segment electrodes of the liquid crystal display to cause an "F" to be displayed. The fault indication can be reset either by the slow discharge of the second capacitor, or by discharging the second capacitor through a second reed switch manually actuated by a magnetic reset tool from outside the fault indicator housing. The "N" display segment electrodes are capacitively coupled to the monitored conductor and system ground to provide an "N" display indicating that voltage is present on the conductor.
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"Liquid Crystal Display", a publication of Hamlin Inc., Lake and Grove Streets, Lake Mills, Wis., circa Jun. 1, 1989.
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